Animal Physiology Quiz: Nervous System

Nervous System

• The nervous system has two main communication systems: the nervous system and the endocrine system.
• The nervous system uses nerves to respond to internal and external stimuli, while the endocrine system uses hormones.

Neuron Structure

• Neurons have three main parts: dendrites, cell body, and axon.
• The axon is surrounded by a myelin sheath, which speeds up the transmission of action potentials.
• The myelin sheath has gaps called nodes, where impulses jump to increase speed.
• "White matter" refers to groupings of myelinated axons, while "gray matter" refers to groupings of neuron cell bodies, dendrites, and synapses.

Nerves

• Nerves are bundles of neurons.
• The myelin sheath insulates axons and has gaps called nodes.
• Impulses jump from node to node, increasing speed.

Chemical Synapse

• An impulse opens ion channels for calcium, which initiates the release of neurotransmitters.
• Neurotransmitters are released from vesicles and cross the synaptic cleft, attaching to protein receptors on the dendrite.
• This interaction opens post-synaptic membrane ion channels for sodium.
• After transmission, neurotransmitters are either degraded or taken back into the presynaptic membrane.

Central Nervous System

• The central nervous system consists of the brain and spinal cord.
• It is the control center of the body, responsible for controlling, receiving, and interpreting stimuli.
• It sends nerve impulses to instruct muscles and glands to take action.

Brain

• The brain weighs about 3 pounds in adults and contains over 100 billion neurons.
• It controls bodily functions and interactions with the outside world.
• The brain has four main divisions: cerebrum, diencephalon, cerebellum, and brain stem.

Cerebrum

• The cerebrum is the most highly developed part of the brain, making up about 80% of its weight.
• It is responsible for thought, decision making, creativity, language, senses, memory, and voluntary control of movement.

Diencephalon

• The diencephalon is the deep portion of the brain containing the thalamus and hypothalamus.
• The thalamus is a relay station for synaptic input, crude awareness of sensation, and role in motor control.
• The hypothalamus regulates homeostatic functions, links the nervous and endocrine systems, and is involved with emotion and behavior.

Cerebellum

• The cerebellum maintains balance, enhances muscle tone, and coordinates skilled voluntary muscle activity.

Brain Stem

• The brain stem connects the brain to the spinal cord and is made up of the midbrain, pons, and medulla oblongata.
• The midbrain is involved with visual reflexes, the pons helps relay messages from the cortex and cerebellum, and plays a key role in sleep and dreaming.

Spinal Cord

• The spinal cord is connected to the spinal nerves, which branch out and connect the brain to the body.
• There are 31 pairs of spinal nerves, each named according to the region of the vertebral column.
• The spinal cord has a butterfly-shaped gray matter region surrounded by white matter.

Peripheral Nervous System

• The peripheral nervous system consists of 12 pairs of cranial nerves and 31 pairs of spinal nerves.
• It receives and processes sensory input from the skin, muscles, tendons, joints, eyes, tongue, nose, and ears, and excites the voluntary contraction of skeletal muscles.

Sense Organs

• Sense organs have sensory receptors that are concentrated in the eyes, ears, nose, mouth, and skin.
• The five general categories of sensory receptors are pain receptors, thermo receptors, mechanoreceptors, chemoreceptors, and photoreceptors.
• The 5 senses are seeing, hearing, smell, taste, and touch.

Resting Nerve

• Nerve impulses are electrical, created by a sodium-potassium pump that uses ATP to pump sodium ions out and potassium ions in.
• This results in a negative charge inside the cell membrane and positive charge outside, creating a resting potential.

Nerve Impulse

• An impulse begins when a neuron is stimulated, causing positively charged sodium ions to flow in and temporarily reversing the charge of the cell membrane.
• As the impulse passes, positively charged potassium ions flow out, restoring the normal resting potential.